A technology has been known in which simulation is performed using a circuit model representing an analog integrated circuit to verify the analog integrated circuit thereby evaluating the performance of the analog integrated circuit. See, for example, Japanese Laid-open Patent Publication No. 11-306230 and Japanese Laid-open Patent Publication No. 2004-94402.
Further, another technology has been known in which a functional relationship is generated by giving the value of a variable regarding the variation of an integrated circuit manufacturing process to the functional relationship to obtain a performance value of the analog integrated circuit in the verification of the analog integrated circuit, in order to analyze the performance variation of the analog integrated circuit out of the variations in a semiconductor integrated circuit manufacturing process which manufactures the analog integrated circuit. See, for example, the non-patent literature 1 entitled “Statistical Regression for Efficient High-Dimensional Modeling of Analog and Mixed-Signal Performance Variations”, appeared in Design Automation Conference, 2008, p. 38-43 Xin Li et al, and another non-patent literature 2 entitled “Finding Deterministic Solution from Underdetermined Equation: Large-Scale Performance Modeling by Least Angle Regression”, appeared in Design Automation Conference, 2009, p. 364-369, Xin Li.
The simulation for analyzing the variations on the performance of the analog integrated circuit, especially for the variations on the performance of the post-layout circuit, is known to be very heavy and thus, a sufficient accuracy of analysis may not be obtained within a scheduled completion date for verification, which is problematic. In the non-patent literature 2, the performance variation model may be created using only parameters that sufficiently influence on the variations on the performance to run a simulation having a good balance between the accuracy of the analysis and time. However, when the number of times to run simulation (hereinafter, referred to as “the number of simulation runs”) is extremely low, it is hard to evaluate whether the functional relationship is suitable for the simulation with a high accuracy due to the difference between respective performance values obtained by the functional relationship and the simulation. In the meantime, it takes time to increase the number of simulation runs. Accordingly, there is a problem that it is hard to efficiently evaluate whether the functional relationship is suitable for the simulation.